# Polarization-control of absorption of virtual dressed-states in helium

## TL;DR

This study demonstrates how changing the relative polarization of infrared and extreme ultraviolet fields can control the absorption features of helium atoms dressed by an infrared pulse, enabling manipulation of light-induced atomic states.

## Contribution

It introduces a method to control atomic absorption spectra by polarization rotation, supported by experimental data and theoretical analysis using Schrödinger and Floquet theories.

## Key findings

- Absorption features are strongly modified or eliminated by polarization rotation.
- Experimental results align with Schrödinger equation simulations.
- Floquet analysis explains the properties of light-induced states.

## Abstract

The extreme ultraviolet absorption spectrum of an atom is strongly modified in the presence of a synchronized intense infrared field. In this work we demonstrate control of the absorption properties of helium atoms dressed by an infrared pulse by changing the relative polarization of the infrared and extreme ultraviolet fields. Light-induced features associated with the dressed $1s2s$, $1s3s$ and $1s3d$ states, referred to as $2s^{+}$, $3s^{\pm}$ and $3d^{\pm}$ light induced states, are shown to be strongly modified or even eliminated when the relative polarization is rotated. The experimental results agree well with calculations based on the solution of the time-dependent Schr\"{o}dinger equation using a restricted excitation model that allows efficient treatment of the three dimensional problem. We also present an analysis of the light induced states based on Floquet theory, which allows for a simple explanation of their properties. Our results open a new route to creating controllable superpositions of dipole allowed and non-dipole allowed states in atoms and molecules.